(Closed) Houston, We Have A Problem

I have a problem I need your assistance with! I am (finally) about to send out my save the dates and I have been stuffing envelopes all day. Here is the issue. Due to the size of the coasters as well as the way I tied them, the envelopes are not exactly stayed sealed once I lick and seal them. What are you suggestions for ways to keep them closed but still look nice?